no ferts now, just soil substrate. (tempted to break the whole thing down, the only thing in there that will even care about the soil is dwarf sag and maybe vallis.

I'm not using any ferts now... I was hoping some natural elements from the soil would dissolve into the water. :/

Ah, this is the 5g soil substrate4 tank, now I remember. I probably wouldn't rush into liquid fertilizer just yet, some of the ideas above may well apply. After a few weeks, if the plants are not showing normal growth--and without fish or ferts don't expect them to grow as they would in a fish tank with more nutrients--a comprehensive liquid may be necessary. Stem plants will not received a great deal of nutrients from the substrate, they also assimilate nutrients form the water column, and although I have often wondered if nutrients in the soil would leech into the water column, the advocates of this method say not, so they may be correct. If the Vallisneria and Sasgittaria do well after an initial acclimation period, and the stem plants do not, this will then definitely be the reason, and liquid ferts will be required.

The aquarist is one who must learn the ways of the biologist, the chemist, and the veterinarian.[unknown source]

Something we all need to remember: The fish you've acquired was quite happy not being owned by you, minding its own business. If you’re going to take it under your wing then you’re responsible for it. Every aspect of its life is under your control, from water quality and temperature to swimming space. [Nathan Hill in PFK]

You may well consider it torture, but I placed some of my guppy fry "culls" into the 5G to help cycle it, along with a ramshorn. (the MTS in my 10G's are hidden :p)

I'm doing daily WC's and gravelvac-ing to help aerate the gravel and suck up the soil-silt that settled on top of the gravel. I know it was a bad idea, but I got some black sand (craft sand) washed it well, and added just a tiny bit to the tank.
(literally, a tiny bit. less than 1/4 cup spread out, ended up being about 1-2 cm, less in most places) to help keep the dirt from mixing with the water. the ramshorn I put in seems to like it, he can reach his food easier.

You may well consider it torture, but I placed some of my guppy fry "culls" into the 5G to help cycle it, along with a ramshorn. (the MTS in my 10G's are hidden :p)

I'm doing daily WC's and gravelvac-ing to help aerate the gravel and suck up the soil-silt that settled on top of the gravel. I know it was a bad idea, but I got some black sand (craft sand) washed it well, and added just a tiny bit to the tank.
(literally, a tiny bit. less than 1/4 cup spread out, ended up being about 1-2 cm, less in most places) to help keep the dirt from mixing with the water. the ramshorn I put in seems to like it, he can reach his food easier.

It's not torture, in a planted tank with this reasonable load there is no "cycle" so the fish will never know it.

I would not recommend vacuuming the substrate at all. Especially as you want to avoid fertilizer; the only source of nutrients (mineral) will be what settle on the substrate and is processed by bacteria. Most of the planted tank folks will tell you not to vacuum the substrate, it will remove precious nutrients.

The aquarist is one who must learn the ways of the biologist, the chemist, and the veterinarian.[unknown source]

Something we all need to remember: The fish you've acquired was quite happy not being owned by you, minding its own business. If you’re going to take it under your wing then you’re responsible for it. Every aspect of its life is under your control, from water quality and temperature to swimming space. [Nathan Hill in PFK]

It's not torture, in a planted tank with this reasonable load there is no "cycle" so the fish will never know it.

I would not recommend vacuuming the substrate at all. Especially as you want to avoid fertilizer; the only source of nutrients (mineral) will be what settle on the substrate and is processed by bacteria. Most of the planted tank folks will tell you not to vacuum the substrate, it will remove precious nutrients.

Guess I'll have to "suck it up" then. I was just doing it for appearences.
I'm not sure what it is... I consider the tank heavily planted, but the fish obviously don't.

Occasionally they gasp for air at the surface. I do a WC and they seem fine for a while. (I let them tell me when I need a W/C.
Maybe they gasp for air when the ammonia gets too high?
I was assuming it was lack of oxygen.

Guess I'll have to "suck it up" then. I was just doing it for appearences.
I'm not sure what it is... I consider the tank heavily planted, but the fish obviously don't.

Occasionally they gasp for air at the surface. I do a WC and they seem fine for a while. (I let them tell me when I need a W/C.
Maybe they gasp for air when the ammonia gets too high?
I was assuming it was lack of oxygen.

The aquarist is one who must learn the ways of the biologist, the chemist, and the veterinarian.[unknown source]

Something we all need to remember: The fish you've acquired was quite happy not being owned by you, minding its own business. If you’re going to take it under your wing then you’re responsible for it. Every aspect of its life is under your control, from water quality and temperature to swimming space. [Nathan Hill in PFK]

Well I checked it a couple days ago...
I can tell you with absolute certainty that the PH is low (around 6.0) and the GH and KH are both less than 3.
I have some dolomite in it, but without water movement I'm not sure if they'll do anything.
(Especially since the dolomite has had 0 effect on my filtered 10G guppy tank)

EDIT-
measured the water. (I do w/cs 1-2 times a day. I did one this morning.)

Well I checked it a couple days ago...
I can tell you with absolute certainty that the PH is low (around 6.0) and the GH and KH are both less than 3.
I have some dolomite in it, but without water movement I'm not sure if they'll do anything.
(Especially since the dolomite has had 0 effect on my filtered 10G guppy tank)

EDIT-
measured the water. (I do w/cs 1-2 times a day. I did one this morning.)

PH- 6.8
GH- 3
KH- 2

Thought so. That's the problem with the guppys. They do not do well in acid or soft water, they require hard basic water, pH mid 7's is best. In too soft/acid water, they will have trouble respirating. Other symptoms may include cloudiness on the skin and erratic movements, then death. Acidosis is the term. The internal blood pH has to be regulated by the fish to the pH of the water the fish swims in, because water is constantly passing through the cells into the fish (this is how fish "drink"); this occurs in all freshwater fish, which is why straying from the "preferred" range or any sudden fluctuations take such a toll on fish health.

The aquarist is one who must learn the ways of the biologist, the chemist, and the veterinarian.[unknown source]

Something we all need to remember: The fish you've acquired was quite happy not being owned by you, minding its own business. If you’re going to take it under your wing then you’re responsible for it. Every aspect of its life is under your control, from water quality and temperature to swimming space. [Nathan Hill in PFK]

Thought so. That's the problem with the guppys. They do not do well in acid or soft water, they require hard basic water, pH mid 7's is best. In too soft/acid water, they will have trouble respirating. Other symptoms may include cloudiness on the skin and erratic movements, then death. Acidosis is the term. The internal blood pH has to be regulated by the fish to the pH of the water the fish swims in, because water is constantly passing through the cells into the fish (this is how fish "drink"); this occurs in all freshwater fish, which is why straying from the "preferred" range or any sudden fluctuations take such a toll on fish health.

my guppy tank has the same PH. After many attempts to fix the PH in THAT tank, I've given up. They're going to have to live with it.

It's got to be something different in the 5G, since the guppies in the 10G are in similiar conditions with no symptoms.

The aquarist is one who must learn the ways of the biologist, the chemist, and the veterinarian.[unknown source]

Something we all need to remember: The fish you've acquired was quite happy not being owned by you, minding its own business. If you’re going to take it under your wing then you’re responsible for it. Every aspect of its life is under your control, from water quality and temperature to swimming space. [Nathan Hill in PFK]